LeetCode 435.

package lc_435;

import java.util.Arrays;
import java.util.Stack;

public class Solution {
    public int eraseOverlapIntervals(int[][] intervals) {
        if(intervals == null || intervals.length == 0) return 0;
        Arrays.sort(intervals, (a,b)->Integer.compare(a[0],b[0]));
        int ans = 0;
        int previous = 0;
        int n = intervals.length;
        for(int current = 1; current < n; current++) {
            if(intervals[current][0] < intervals[previous][1]) {
                ans++;
                if(intervals[current][1] <= intervals[previous][1]) {
                    previous = current;
                }
            }
            else {
                previous = current;
            }
        }
        return ans;
    }
}